Rust inhibited distillate products



nited States, Patent cc RUST INHIBITED DISTILLATE PRODUCTS Harry W.Rude], Roselle Park, and Marion Gargisa, Elizabeth, N. 1., assignors toEsso Research and Engineering Company, a corporation of Delaware NoDrawing. Application December 12, 1952, Serial N0. 325,694

3 Claims. (Cl. 44-72) phosphoric acid or a free cyclo-alkyl phosphoricacid I.

or a soap of these acids. Mixed salts of the two constituents may alsobe employed. Particularly desirable product-soluble rust inhibitors ofthis class are the am: monium salts of petroleum sulfonic acid and analkyl phosphoric acid.

A problem which has long existed in the handling and i use of petroleumproducts is the rusting which frequently occurs in pipelines, storagetanks, engines, etc. Old as this problem is, eflective means of meetingthe problem have only been suggested in recent years.

covery of elfective rust inhibitors for petroleum products; The rustingproblem which occurs in storing and using petroleum products occurs asthe result of traces of A good deal of technical consideration is nowbeing given to the dismoisture inevitably present in petroleumdistillates. {i

Moisture finds its way into the distillates in a variety of ways. WhileWater is not appreciably soluble in petroleum distillates traces ofmoisture are, in fact, dissolved in heating oil, gasoline, kerosene,etc. Again, it is impossible to prevent entrainment of moisture in suchproduc'ts during storage and handling. In this connection, for example,storage tanks are generally provided with breather devices to permit theintake and exhaust of air during atmospheric changes. As a result, cool,moisture resulting in the condensation of moisture in the tank. Aportion of this moisture is dissolved in or entrained in petroleumproducts when pumped from the storage tanks.

There have been a number of suggestions for overcoming the corrosion dueto moisture carried by oil products. Forexample, a number ofwater-soluble rust inhibitors are known and have been employed; Use ofwater-soluble inhibitors is disadvantageous for several reasons,however. The inhibitor is largely lost when water is separated from oilproducts during handling so that the desired rust inhibition forremaining residual traces of water may be lost. 'Addition ofwater-soluble inhibitors to oil again necessarily requires addition ofwater to the oil which aggravates the problem'intended to be solved. Itis therefore a particularobject of this invention to provide a rustinhibitor which is soluble in the oil product to be inhibited. 1

It may be observed that attempts have been 'made'in' the past 'toprovide suitable oil-soluble rust inhibitors.

laden air is generally drawn into a storage tank at night,

2,791,495 r Patented .lvlay 7, 1957 is the tendency of many inhibitorsto discolor dyed gasolines. A more specific object of this inventiontherefore is to provide an oil soluble rust inhibitor which'willsuitably'inhibit an oil product against rusting, while in no way'afiecting the critical inspections or characteristics of the oilproduct. i

These objectives are satisfied in accordancewith this invention by atwo-component rust inhibitive composition. The makeup of thiscomposition is based on the discovery that two particular classes ofrust inhibitors are beneficially employed in combination to obtain rustinhibiting characteristics unobtainable by use of single componentsselected from either class of inhibitors. In other words the inventionis based on the discovery of a synergistic action between two classes ofrust inhibitors. In this combination one inhibitor constitutes a salt ofa hydro carbon sulfonic acid. As well known to the art, hydrocarbonsulfonic acids are oil-soluble sulfonic acids obtained by thesulfonation of a hydrocarbon oil. Forexample, in the courseof white oilproduction, sulfuric acid is employed to treat a hydrocarbon oil.Reaction of the sulfuric acid with the hydrocarbon oil results in theformation of oil-soluble annd water-soluble petroleum sulfonic acids.The oil-soluble sulfonic acids are conventionally called mahoganysulfonic acids. Other sulfonic acids from different sources may beemployed such as those of alkylated aromatics, e. g., polypropyl'benzeneor wax-alkylated toluene, or those formed by the sulfonationof wax.Salts or-soaps of these acids are formed by reaction of a basic compoundwith the sulfonic acid and these soaps are to be employed in thisinvention. For example, an oil-soluble alkali metal or alkaline earthmetal soap or mahogany sulfonic acid may be em ployed. The ammonium soapor mahogany sulfonic acid may be used advantageously. The ammonium soapis particularly desirable for use in this invention since this soapforms no ash when the oil product, in which the inhibitor is used, isburned. a

The second constituent of therust inhibiting composi tion of thisinvention is an alkyl or cyclo-alkyl phosphoric acid or a salt of analkyl or cyclo-alkyl phosphoric acid. Consequently, as used herein, theterms alky and aliphatic include cycle-alkyl and cyclo-aliphatic. Theseacids are preferably prepared by the reaction of P205 with an alcohol.The preferred alcohols to be reacted are the monohydric primary alcoholshaving 6 to 13 carbon atoms. While aliphatic alcohols of this characterare preferred, aryl alcohols may also be employed. The reaction betweenP205 and the alcohol results in the formation of what may be calledesters or acid-Esters of phosphoric acid. Depending upon thereactantproportions and the reaction conditions, mono-, di-, or tri-alkylphosphoric acids may be obtained. Practically the reaction productconstitutes a mixture of the esters. For this reason this constituent ofthe rust inhibiting composition is best defined as the reaction productof P205 The problem of providing such an inhibitor 'is complicated 1 gand an alcohol. V

The two-component rust inhibiting composition may also be prepared bymixing a hydrocarbon sulfonic acid with an alkyl phosphoric acid andforming a mixed salt of these acids. As examples of this procedure,ammonia or sodium hydroxide may be reacted with the mixed acids to formmixed soaps of the sulfonic acid and alkyl phosphoric acid. I

In order to obtain the desired synergism between the salt of hydrocarbonsulfonic acid and the alkyl phosphoric acid or its salt, theseconstituents should be combined in proportion ranging from about 1 to0.5, to 1 to 12. A preferred synergistic combination of the twoadditives'employs'about 1 part of the scia'pbf'sulfonic ticular problemencountered with gasoline inhibitors A acid an'd'about' 3 parts ofan'alkyl phosphoric'acid' or its ratios given are expressed on a weightbasis.

Examples of suitable alkyl phosphoric acid soaps are mono-laurylphosphoric acid, di-octyl phosphoric acid, di-Z-ethyl-hexyl phosphoricacid, di-lauryl phosphoric acid, di-butyl phosphoric acid,mono-octadecyl phosphoric acid, cyclo hexyl phosphoric acid, methylcyclo hexyl phosphoric acid, etc. Of these compounds, Cs alkylphosphoric acids are particularly preferred for use in this invention.

The combined rust inhibiting additives, in the ratios indicated, may beemployed economically in petroleum products in the concentration ofabout pound per 1,000 barrels up to 25 pounds or more per 1,000 barrels.In this range of concentrations it is generally suitable and preferredto use a concentration of about 1 to 5 pounds of combined rustinhibitors per 1,000 barrels of product. Of course, in specialcircumstances where the primary function of the oil composition may bethat of rust prevention, it is practicable and desirable to use higherconcentrations of the combined rust inhibiting additives up to the limitof their solubility in oil. The oil products which may be successfully'inhibited'in this way may be defined as the distillate petroleumproducts. Thus, the oil product may constitute gasoline, l erosene,lubricating oil, heating oil, gas oil, etc.

In order to demonstrate the utility and benefits of this invention, thefollowing examples are presented. -In these a rusting test was employedwhich generally corresponds to A. S.-T. M. test method D-665. This testwas modified however, by lowering the temperature to 77 F. The testrequired stirring of a mixture of 300 cc. of oil product with 30 cc. ofdistilled water at 77 F. with a cylindrical steel rod immersed therein.At the end of 24hours the rod was examined and rated in accordance withthe amount of rust which had formed. In a first series of tests whichwere conducted, the ammonium salt of petroleum sulfonic acid wasemployed as the first constituent of the rust inhibiting composition.The second constituent constituted the ammonium soap of the reactionproduct of phosphoric pentoxide and isooctyl alcohol synthesized by thex0 process. To obtain the phosphoric acid, 66 g. (0.5 mole) ofphosphorus pentoxide was added portionwise with stirring to 260 g; (2moles) of iso-octyl alcohol at about 60 (3., following which stirringwas continued for 2 hours at 60 C. The reaction product was heated to140 C. and blown with nitrogen under reduced pressure for 4 hours toexpel unreacted alcohol and water formed during the reaction. To preventdarkening the product during the heating period, a'trace of-tri-sodiumphosphate may be added-if desired. A stream of ammonia was passed intothis 'reaction product that hadbeen diluted with a solvent until ammoniawas'nolonger absorbed. Excess ammonia was removed by blowing withnitrogen at elevated temperatures.

Rust tests were then conducted on a heating oil containingsmall portionsof the constituents described. The heating oil employed had thefollowing inspections:

TABLE I Inspections on heating oil The data obtained from :he rustingtests is indicated in the following Table II:

TABLE II Modified A. S. T. M. rust tests (24 hours at 77 F.)

[Blends in heating 011.]

1 Two acids were combined and neutralized with ammonia.

It will be noted that as'shovvn by thesedata that heat: ing oil alonewas characterized by heavy rusting under the conditions of the test.When one pound per 1,000. barrels of either of the ammonium salts wereemployed individually, rusting was still encountered. However, whenusing only 1 pound per 1,000 barrels of an equal weight proportionmixture of the ammonium salt of petroleum sulfonic acid and the ammoniumsalt of Oxo phosphoric acid, the rusting was completely eliminated.

Similar tests were then conducted employing the sodium salt of petroleumsulfonic acid and the free isooctyl phosphoric acid. The data obtainedin rusting tests is shown in the following Table III:

TABLE III Modified A. S. T. M. rust tests (24 hours at 77 F.) [Blends inN o. 2 heating 011.]

Inhibitor (cone. in Wt. percent) 1 Extent of Busting 0.00025% isooctylphosphoric acid Heavy. 0.0005% Sodium petroleum sulfonate Heavy.

0.000125% Isooctyl phosphoric acid-l-0.000125% sodium Trace.

. petroleum sultonate.

0.000125% isooetyl phosphoric acid-l-0.000063% sodium Very light.

petroleum sultonate.

None Heavy.

- I 1#/1,000 bbls.=0.00033 wt. percent approximately.

Effect of rust inhibitors in various base stocks [Modified A. S. '1. M.rust test-24 hrs. at 77 F.]

Rust Rating at Follow- '1. E. L. Boiling ing Inhibitor Cone. Base StockContent, Range (#[1000 bbls.)

. cit/gal. (F.)

None 1# '21? '31! Regular Gaso1ine. 1. -425 R-6 R -4 R-i R-I PremiumGasoline 2. 7 100-400 R-4 R-l R-1 R-l 91/98 Aviation Gas- 4. 0 100-330R-7 R-6 lit-8 R-i /145 Aviation Gas. 4.6 100-330 R-7 R-l R-l R-1Kerosene 300-550 R-7 R-l It-l R-l 1 Inhibitor consists of ammonium saltsof mahogany sull'onic acid and isooetylphosphoric acid in 1/2 weightratio. Rating System: 1

, R-l, No rusting.

R-2, Trace rusting. 3-3, Less than 5% surface rusted. R-4, Between 5 and50% of surface rusted. R-B, Between 50 and 99% of surface rusted. R-ti,100% of surface wlthlightrust. 113-7, 100% of surface with heavy rust.

TABLE V Effect of varying the sulfonate to phosphate ratio [Modified A.S. T. M. rust test-24 hrs. at 77 F.]

Rust; Rating at Following Inhibltor Gone. (#[1000 bbls.)

Wt. Ratio of Sulfonate to Phosphate None 1# 2# 3# 4# 5# It will be notedfrom the data of Table V that rust inhibition was secured over the rangeof inhibitor proportions used. However, shbstantially better rustinhibition was obtained at sulfonate to phosphate ratios of 1/ 2 or 1/3than at 1/12. Again, the data shows that more than about 3 pounds ofinhibitor composition are preferably employed for 1000 barrels ofproduct.

The combination additive exhibits an additional advantage in that in aconcentrated oil solution the ammonium mahogany sulfonate prevents thecrystallization of the ammonium isooctyl phosphate. The latter, byitself, tends to precipitate from an oil solution of or higherconcentration, whereas in the presence of the sultonate, a concentrateshows no crystallization. This ability to prepare concentrates isimportant in the manufacture, transportation and application of rustinhibiting additives.

The rust inhibiting additives of this invention are advantageouslyprepared for use by solution in an oil vehicle. The particular oilchosen for preparation of the inhibitor concentrate is chosen withregard to the product in which the concentrate is to be used; preferablyhaving about the boiling range of the product.

What is claimed is:

1. A fuel composition comprising a petroleum distillate fuel and from0,00008 to about 0.00825 wt. percent of a mixture of a soap of anoil-soluble petroleum sulfonic acid selected from the group consistingof sodium and ammonium petroleum sulfonates, and a compound selectedfrom the group consisting of isooctyl phosphoric acid and an ammoniumsalt of an isooctyl phosphoric acid, the proportions of said petroleumsulfonate to said last-named constituent being in the range of from 1:05to 1:10.

2. The composition of claim 1 in which said petroleum sulfonate is anammonium petroleum sulfonate.

3. The composition of claim 2 in which the last-named constituent is anammonium salt of isooctyl phosphoric acid.

References Cited in the file of this patent UNITED STATES PATENTS2,080,299 Benning May 11, 1937 2,550,982 Eberz May 1, 1951 2,594,266Watkins Apr. 22, 1952 2,632,694 Watkins Mar. 24, 1953 2,650,198 KronigAug. 25, 1953

1. A FUEL COMPOSITION COMPRISING A PETROLEUM DISTILLATE FUEL AND FROM0.00008 TO ABOUT 0.00825 WT. PERCENT OF A MIXTURE OF A SOAP OF ANOIL-SOLUBLE PETROLEUM SULFONIC ACID SELECTED FROM THE GROUP CONSISTINGOF SODIUM AND AMMONIUM PETROLEUM SULFONATES, AND A COMPOUND SELECTEDFROM THE GROUP CONSISTING OF ISOOCTYL PHOSPHORIC ACID AND AN AMMONIUMSALT OF AN ISOOCTYL PHOSPHORIC ACID, THE PROPORTIONS OF SAID PETROLEUMSULFONATE TO SAID LAST-NAMED CONSTITUENT BEING IN THE RANGE OF FROM1:0.5 TO 1:10.